JP2002178645A - Heat sensitive recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sensitive recording body which is highly stable to a plasticizer or the like and the remarkably improved recording sensitivity. SOLUTION: In the heat sensitive recording body in which a recording layer mainly including a colorless or light-colored basic dye and an organic developer is provided on a support, the heat sensitive recording layer includes a urea urethane compound represented by general formula (1) as the organic developer and, at the same time, at least one kind of a compound represented by general formula (2), in which, R1 represents a 1-4C alkyl group, aralkyl group, a phenyl group or a hydrogen atom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium having excellent storage stability of a color image and excellent color sensitivity.

[0002]

2. Description of the Related Art In general, a thermosensitive recording medium is prepared by grinding and dispersing a colorless or pale-colored basic colorless dye and an organic developer such as a phenolic compound into fine particles, and then mixing the two. A paint obtained by adding a binder, a filler, a sensitivity enhancer, a lubricant and other auxiliaries is applied to a support such as paper, synthetic paper, film, plastic, etc.
Color is formed by an instantaneous chemical reaction due to heating of a thermal head, hot stamp, hot pen, laser light, etc., and a recorded image is obtained. Thermal recording media are facsimile, computer
Terminal printer, automatic ticket vending machine, measurement recorder
Widely used for etc. In recent years, high-speed printing and high-speed image formation have become possible with the diversification of recording apparatuses and the advancement of high performance, and higher quality is required for the recording sensitivity of the thermosensitive recording medium. As a method for satisfying this requirement, it has been proposed to use a dye and a developer together with a sensitizer. For example, if the developer is bisphenol A
In the case of a phenolic compound represented by p-benzylbiphenyl (JP-A-60-82382), p-benzylbiphenyl
Benzyl benzyl benzoate (JP-A-57-201)
No. 691), benzyl naphthyl ether (JP-A-58-1983).
No. 87094) is used as a suitable sensitizer. When a sensitizer is used, the sensitizer is first melted when heated, and this dissolves the basic dye and the developer so that they mix at the molecular level and induce a color-forming reaction. It is important to consider sensitizers, basic dyes and developers. In particular, when the recording sensitivity is improved with a sensitizer or the like, the storage stability of the recorded image often cannot be maintained. Specifically, the sebum component adheres or the plasticizer (DOP,
(DOA etc.), there still remain disadvantages such as a marked decrease in image density and decoloration. Furthermore, in recent years, with the increasing use in fields such as labels that require reliability in recorded images, high storage stability against plasticizers, oils and fats contained in packaging materials and the like has been achieved. There is a need for the recording materials shown. Until now, various dyes, developers,
Alternatively, thermal recording media using various auxiliaries such as storage stabilizers have been proposed, but none of them have been found to be sufficiently satisfactory.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording medium which has high stability against plasticizers and the like and has greatly improved recording sensitivity.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a thermosensitive recording medium having the above-mentioned performance, and as a result, have used an urea urethane compound as a developer and an aminosulfonyl group ( By using an aromatic compound having —SO ₂ NH ₂ ) as a sensitizer, the recording sensitivity was greatly improved, and the present invention was completed. That is, the present invention relates to a heat-sensitive recording medium having a heat-sensitive coloring layer containing a colorless or pale-colored basic colorless dye and an organic color developing agent as main components on a support. This has been achieved by containing a ureaurethane compound represented by the following general formula (1) as an agent and at least one compound represented by the following general formula (2).

[0005]

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[0006]

Embedded image (In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms, an aralkyl group, a phenyl group, or a hydrogen atom.) For the color developer represented by the general formula (1), The compound to be used is effective as a sensitizer because both have a sulfonyl group and thus have good compatibility. Further, the compound represented by the general formula (2) is used as a solvent when it is melted by heat. It is presumed to be due to the action.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, a thermosensitive recording medium is prepared by dispersing a colorless or pale-colored basic dye and a developer together with a binder, and optionally sensitizing agents, fillers, ultraviolet absorbers, water-proofing agents, and the like. It is produced by preparing a paint by adding an auxiliary agent such as an antifoaming agent, applying the paint on a support, and drying.
In the present invention, at least one urea urethane compound represented by the general formula (1) is used as an organic developer. Specific examples of the compound represented by the general formula (1) are given below.

[0008]

Embedded image In the present invention, at least one compound represented by the general formula (2) is used as a sensitizer. In the general formula (2), R ₁ may be any substituent that does not inhibit the sensitizing effect, and examples of such a substituent include an alkyl group having 1 to 4 carbon atoms, an aralkyl group, a phenyl group, and hydrogen. Atoms and the like. Specific examples of the compound represented by the general formula (2) are shown below as (2-1) to (2-11).
But are not limited to these.

[0009]

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[0010]

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[0011]

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[0012]

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[0013]

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In the present invention, two or more kinds of the compounds represented by the general formula (2) can be mixed and used at a molecular level. The mixing at the molecular level in the present invention means
It is obtained by a method different from mixing at the particle level, such as simply mixing the two dispersions or mixing and dispersing the two powders during dispersion. That is, the molecular level mixture in the present invention is obtained by a method of hot-melting the two to obtain a mixture, a method of dissolving the mixture in a solvent and then depositing the mixture to obtain a mixture, or a method of depositing the mixture as it is after synthesizing the compound of the general formula (2). It is prepared by a method such as For example, the melting point of (2-2) used in the present invention is about 154 to 156 ° C, and the melting point of (2-4) is about 136 ° C.
138 ° C. The melting point of the mixture at the molecular level is lowered by the eutectic point effect, and an excellent sensitizing effect is obtained. The melting temperature changes depending on the mixing ratio of the two,
Particularly, the mixing weight ratio of (2-2) and (2-4) is 35: 6.
When the ratio is in the range of 5 to 45:55, the melting temperature of these molecular level mixtures drops to about 100 ° C. to about 110 ° C., and an extremely high sensitizing effect can be obtained. In the present invention, if the content of the sensitizer represented by the general formula (2) is too small relative to 1 part of the developer represented by the general formula (1), the sensitizing effect is not sufficient and If it is too high, a sufficient color density cannot be obtained. In the present invention, the sensitizer represented by the general formula (2) is used in an amount of 0.0 to 1 part of the developer represented by the general formula (1).
It is desirable to use 1 to 2 parts. As the colorless or light-colored basic dye used in the heat-sensitive recording medium of the present invention, any known dyes in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and are not particularly limited.
Triphenylmethane compounds, fluorane compounds, fluorene compounds, divinyl compounds and the like are preferred. Specific examples of typical colorless or pale color dyes (dye precursors) are shown below. These dye precursors may be used alone or in combination of two or more.

<Triphenylmethane leuco dye> 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [also known as crystal violet lactone] 3,3-bis (p-dimethylaminophenyl) phthalide [ Malachite green lactone] <Fluoran leuco dye> 3-Diethylamino-6-methylfluoran 3-Diethylamino-6-methyl-7-anilinofluoran 3-Diethylamino-6-methyl-7- (o, p-dimethyl Anilino) fluorane 3-diethylamino-6-methyl-7-chlorofluoran 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-6-methyl-7- (o- Chloroanilino) fluoran 3-diethylamino-6-meth Le-7- (p-chloroanilino) fluoran 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-diethylamino-6-methyl-7- (m-methylanilino) fluoran 3-diethylamino-6 Methyl-7-n-octylanilinofluoran 3-diethylamino-6-methyl-7-n-octylaminofluoran 3-diethylamino-6-methyl-7-benzylanilinofluoran 3-diethylamino-6-methyl- 7-dibenzylanilinofluoran

3-Diethylamino-6-chloro-7-methylfluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-diethylamino-6-chloro-7-p-methylanilinofluoran 3-diethylamino -6-ethoxyethyl-7-anilinofluoran 3-diethylamino-7-methylfluoran 3-diethylamino-7-chlorofluorane 3-diethylamino-7- (m-trifluoromethylanilino) fluoran 3-diethylamino- 7- (o-chloroanilino) fluoran 3-diethylamino-7- (p-chloroanilino) fluoran 3-diethylamino-7- (o-fluoroanilino) fluoran 3-diethylamino-benzo [a] fluoran 3-diethylamino-benzo [c Fluorane 3-dibutyl Mino-6-methyl-fluoran 3-dibutylamino-6-methyl-7-anilinofluoran 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluoran 3-dibutylamino-6 Methyl-7- (o-chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (p-chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-dibutylamino -6-methyl-7- (m-trifluoromethylanilino) fluoran 3-dibutylamino-6-methyl-7-chlorofluoran 3-dibutylamino-6-ethoxyethyl-7-anilinofluoran 3-dibutyl Amino-6-chloro-7-anilinofluoran 3-dibutylamino-6-methyl-7-p-methyla Linofluoran 3-dibutylamino-7- (o-chloroanilino) fluoran 3-dibutylamino-7- (o-fluoroanilino) fluoran 3-di-n-pentylamino-6-methyl-7-anilinofluoran 3- Di-n-pentylamino-6-methyl-7- (p-
Chloroanilino) fluorane 3-di-n-pentylamino-7- (m-trifluoromethylanilino) fluoran 3-di-n-pentylamino-6-chloro-7-anilinofluoran 3-di-n-pentyl Amino-7- (p-chloroanilino) fluoran 3-pyrrolidino-6-methyl-7-anilinofluoran

3-Piperidino-6-methyl-7-anilinofluoran 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluoran 3- (N-methyl-N-cyclohexyl Amino) -6-
Methyl-7-anilinofluoran 3- (N-ethyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-xylamino) -6-methyl-
7- (p-chloroanilino) fluoran 3- (N-ethyl-p-toluidino) -6-methyl-
7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-chloro-7-anilino Fluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-ethoxypropylamino) -6
-Methyl-7-anilinofluoran 3-cyclohexylamino-6-chlorofluoran 2- (4-oxahexyl) -3-dimethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-diethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-dipropylamino-
6-methyl-7-anilinofluoran 2-methyl-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluoran 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2 -Chloro-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran

2-nitro-6-p- (p-diethylaminophenyl) aminoanilinofluoran 2-amino-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2- Benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluoran 3-methyl-6-p- (p-dimethyl Aminophenyl)
Aminoanilinofluoran 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluoran 2,4-dimethyl- 6-[(4-Dimethylamino) anilino] -fluorane <Fluorene leuco dye> 3,6,6′-tris (dimethylamino) spiro [fluorene-9,3′-phthalide] 3,6,6′-tris (Diethylamino) spiro [fluorene-9,3'-phthalide] <Divinyl leuco dye> 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5
6,7-tetrabromophthalide 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5
6,7-tetrachlorophthalide 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide 3,3- Bis- [1- (4-methoxyphenyl) -1-
(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide

<Others> 3- (4-Diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4-azaphthalide 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) ) -4-Azaphthalide 3,3-bis (1-ethyl-2-methylindole-3
-Yl) phthalide 3,6-bis (diethylamino) fluoran-γ- (3
'-Nitro) anilinolactam 3,6-bis (diethylamino) fluoran-γ- (4
'-Nitro) anilinolactam 1,1-bis- [2', 2 ', 2 ", 2" -tetrakis-
(P-dimethylaminophenyl) -ethenyl] -2,2
-Dinitrileethane 1,1-bis- [2 ', 2', 2 ", 2" -tetrakis-
(P-dimethylaminophenyl) -ethenyl] -2-β
-Naphthoylethane 1,1-bis- [2 ', 2', 2 ", 2" -tetrakis-
(P-dimethylaminophenyl) -ethenyl] -2,2
-Diacetylethane bis- [2,2,2 ', 2'-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

In the present invention, a conventionally known color developing agent which forms a colorless or light-colored basic dye can be used in combination within a range not to impair the desired effect on the above-mentioned problem. However, it is desirable to add a very small amount of the compound.
It is about 01 to 0.9 parts. Examples of such a developer include, for example, JP-A-3-207688 and JP-A-5-2436.
6, bisphenol A, 4-hydroxybenzoic acid ester, 4-hydroxyphthalic acid diester, phthalic acid monoester, bis- (hydroxyphenyl) sulfide, 4-hydroxyphenylaryl sulfone, 4-hydroxyphenylarylsulfonates, 1,3-di [2- (hydroxyphenyl)
-2-propyl] -benzenes, 4-hydroxybenzoyloxybenzoic acid esters, and bisphenolsulfones. In the present invention, conventionally known sensitizers can be used as long as the desired effects on the above-mentioned objects are not impaired. Examples of such a sensitizer include fatty acid amides such as stearamide and palmitamide.
Ethylene bisamide, montanic acid wax, polyethylene wax, 1,2-di- (3-methylphenoxy) ethane, p-benzylbiphenyl, β-benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-
Terphenyl, 1,2-diphenoxyethane, 4,4 '
-Ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, 1,2-di (3-methylphenoxy) ethylene, 1,2-diphenoxyethylene, bis [2- (4-methoxy-phenoxy) ethyl〕
Ether, methyl p-nitrobenzoate, dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p-methylbenzyl) oxalate, dibenzyl terephthalate, p
Benzyl benzyloxybenzoate, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate,
1,4-diethoxynaphthalene, 1-hydroxy-2-
Naphthoic acid phenyl ester, o-xylene-bis-
Examples thereof include (phenyl ether) and 4- (m-methylphenoxymethyl) biphenyl, but are not particularly limited thereto. These sensitizers may be used alone or in combination of two or more.

As the binder used in the present invention, completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl Alcohol, other modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer and cellulose derivatives such as ethyl cellulose, acetyl cellulose, polyvinyl chloride, polyacetic acid vinyl,
Examples thereof include polyacrylamide, polyacrylate, polyvinyl butyl lauryl polystyrene, and copolymers thereof, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, and cumaro resin. These polymer substances can be used by dissolving them in solvents such as water, alcohols, ketones, esters, and hydrocarbons, or they can be used in the form of emulsified or dispersed in water or other media, depending on the required quality. They can be used together. Further, in the present invention, 4,4'-butylidene (6-t-butyl-3-methylphenol) is used as an image stabilizer which exhibits an oil resistance effect of a recorded image, as long as the desired effect on the above-mentioned object is not impaired. ) 2,2'-di-t-butyl-5,5'-dimethyl-4,
4'-sulfonyldiphenol 1,1,3-tris (2-methyl-4-hydroxy-5
-Cyclohexylphenyl) butane 1,1,3-tris (2-methyl-4-hydroxy-5
-T-butylphenyl) butane and the like can also be added.

The filler used in the present invention is silica,
Examples include inorganic or organic fillers such as calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, and aluminum hydroxide. In addition, release agents such as fatty acid metal salts, lubricants such as waxes, benzophenone-based and triazole-based ultraviolet absorbers, waterproofing agents such as glyoxal, dispersants, defoamers, antioxidants,
A fluorescent dye or the like can be used. The amounts of the developer and dye used in the thermal recording medium of the present invention and the types and amounts of other various components are determined according to the required performance and recording suitability, and are not particularly limited. For 1 part of the developer represented by (1), 0.1 to 2 parts of a basic colorless dye, 0.01% of the compound represented by the general formula (2)
2 to 2 parts and 0.5 to 4 parts of filler are used, and the binder is suitably 5 to 25% of the total solid content. The desired heat-sensitive recording sheet can be obtained by applying a coating solution having the above composition to an arbitrary support such as paper, synthetic paper, film, and plastic. Furthermore, an overcoat layer of a polymer substance or the like can be provided on the thermosensitive coloring layer for the purpose of enhancing the storage stability. The above-mentioned organic developer, basic colorless dye, and materials to be added as necessary are pulverized to a particle diameter of several microns or less by a pulverizer such as a ball mill, an attritor, a sand glider or an appropriate emulsifier, and a binder. And various additive materials are added according to the purpose to form a coating liquid. Further, an undercoat layer of a polymer substance containing a filler or the like can be provided below the heat-sensitive layer for the purpose of increasing the coloring sensitivity.

[0023]

EXAMPLES The thermosensitive recording medium of the present invention will be described below with reference to examples. In the description, parts and% represent parts by weight and% by weight, respectively, unless otherwise specified.

Examples 1 and 2 In Examples 1 and 2, the heat-sensitive recording material of the present invention was prepared by adding compound (1-1) or (1-2) as a developer and 3-dibutylamino- as a basic colorless dye. 6-methyl-7-anilinofluoran (ODB-2), a compound (2-
This is an example using 2). A developer dispersion (solution A), a basic colorless dye dispersion (solution B), and a sensitizer dispersion (solution C) having the following composition are separately wet-ground with a sand grinder until the average particle diameter becomes 1 micron. Crushing was performed. Liquid A (Developer dispersion liquid) Developer 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Liquid B (Basic colorless dye dispersion liquid) 3-dibutylamino-6-methyl-7 -Anilinofluoran (ODB-2) 2.0 parts 10% aqueous solution of polyvinyl alcohol 4.6 parts Water 2.6 parts Liquid C (sensitizer dispersion) Compound (2-2) 4.0 parts 10% polyvinyl Aqueous alcohol solution 18.8 parts Water 11.2 parts Next, the dispersion was mixed and stirred at the following ratio to prepare a coating liquid. Liquid A (developer dispersion liquid) 36.0 parts Liquid B (basic colorless dye [ODB-2] dispersion liquid) 9.2 parts Liquid C (sensitizer [compound (2-2)] dispersion liquid) 34 0.0 parts Kaolin clay (50% dispersion) 12.0 parts After applying each of the above coating liquids to one side of a base paper of 50 g / m ² , drying was performed, and the sheet was smoothed with a super calendar at a smoothness of 500 to 600. Seconds to obtain a thermosensitive recording medium having a coating amount of 6.0 g / m ² .

Example 3 In Example 3, compound (1-1) was used as a developer, and 3-dibutylamino-6- was used as a basic colorless dye.
This is an example using methyl-7-anilinofluoran (ODB-2) and compound (2-5) as a sensitizer. A developer dispersion of the compound (1-1) and a sensitizer dispersion of the compound (2-5) were treated in the same manner as in Example 1. Each of the basic colorless dye dispersions (B) was separately wet-ground by a sand grinder until the average particle diameter became 1 μm. Liquid B (Basic colorless dye dispersion) The above basic colorless dye 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.6 parts Next, the dispersion liquid is mixed and stirred at the following ratio, and the coating liquid is prepared. Prepared. Liquid A (Developer dispersion of compound (1-1)) 36.0 parts Liquid B (basic colorless dye dispersion) 9.2 parts Liquid D (sensitizer [compound (2-5)] dispersion 34.0 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above coating solutions was applied to one surface of a base paper of 50 g / m ² , and then dried. The heat treatment was performed so as to result in a coating time of 6.0 g / m ² .

Example 4 In Example 4, compound (1-1) was used as a developer, ODB-2 was used as a basic colorless dye, and compound (2-) was used as a sensitizer.
This is an example using 6). The developer dispersion of the compound (1-1) and the ODB-2 dispersion were treated in the same manner as in Example 1, and the compound (2-6) was treated in the same manner as the compound (2-2). Liquid). Next, the dispersion liquid was mixed and stirred at the following ratio to prepare a coating liquid. Liquid A (developer liquid dispersion of compound (1-1)) 36.0 parts Liquid B (basic colorless dye [ODB-2] dispersion) 9.2 parts Liquid E (sensitizer dispersion) 34. 0 parts Kaolin clay (50% dispersion) 12.0 parts After applying each of the above coating liquids to one side of a base paper of 50 g / m ² , drying is performed, and the sheet is smoothed with a super calendar at a smoothness of 500 to 600 seconds. To obtain a thermosensitive recording medium having a coating amount of 6.0 g / m ² .

Comparative Example 1 The same operation as in Example 1 was performed. However, the dispersion C used in Examples 1 to 4 was not mixed in the formation of the coloring layer.

Comparative Example 2 The same operation as in Example 1 was performed. However, in preparing the dispersion C, p-benzylbiphenyl (PBB) was used instead of the compound (2-2).

[0029]

[Table 1]

<Evaluation of thermal recording medium> The prepared thermal recording medium was measured using TH-PMD (a thermal recording paper printing tester manufactured by Okura Electric Co., Ltd. with a thermal head manufactured by Kyocera Corporation).
Printing was performed with an applied energy of 0.38 mj / dot. The recording density of the recording section was measured with a Macbeth densitometer (RD-914, using an amber filter) (see Tables 1 and 2).

<Evaluation of resistance to plasticizer> A vinyl chloride wrap (High Wrap KMA manufactured by Mitsui Toatsu) was wound around a paper tube in a single layer. Then, a layer obtained by winding PVC wrap three times thereon was allowed to stand at 40 ° C. for 24 hours, and the Macbeth density of the image area was measured. Table 2 shows the evaluation results.

[0032]

[Table 2] As is clear from Tables 1 and 2, the general formula (1)
When the compound represented by the formula (1) is used as a developer, high recording sensitivity is exhibited when the compound represented by the formula (2) is used in combination.
On the other hand, in Comparative Example 2 in which another sensitizer was used, sufficient color-forming ability was not obtained, indicating that the compound represented by the general formula (2) has a remarkable sensitizing effect.

[0033]

The heat-sensitive recording material of the present invention is excellent in image stability such as plasticizer resistance, and has high coloring sensitivity and good recorded image. Therefore, a clear image can be obtained with high sensitivity even with a small amount of energy.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshihide Kimura 5-21-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. F-term (reference) 2H026 AA07 BB24 DD02 DD45

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support having thereon a recording layer containing a colorless or light-colored basic colorless dye and an organic color developer as main components, wherein the heat-sensitive recording layer is used as an organic color developer. A thermosensitive recording material comprising a urea urethane compound represented by the following general formula (1) and at least one compound represented by the following general formula (2). Embedded image Embedded image (In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms, an aralkyl group, a phenyl group, or a hydrogen atom.)